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Arcade Car Physics (ACP)

asset store page extented version asset store page

This unity package provides scripts ans exemples to build arcade cars in Unity3D using the built in wheel colliders. While the wheel colliders have a reputation to be buggy and unstable I found that it is not true but they are a bit tricky to get right.

In this package you'll find one demo scene with 4 exemple prefabs with low poly models made using kenney's asset forge.

Getting Started

First start by changing the inputs in the DemoInputs asset to use inputs in you project settings (Edit > Project Settings > Inputs)

I have errors about missing inputs! Go to your project settings and add the missing inputs
Materials are pink/missing! Unity's rendering pipelines have changed since this plugin started, feel free to change the meshes four your own
How do I change the meshes? Look in the car prefabs, you should find the Body object and replace his children with your own mesh and move the wheels

More documentation can be found here How to create a car, video tutorial, I'm not very good at tutorials so this is just a video of me building on of the cars from the demo.

Vehicle

The typical vehicle's composition is as follow:

├── CarPrefab
│   ├── Body
│   |   ├── 3D mesh REPLACE THIS WITH YOUR OWN MESH
│   ├── Front Left Wheel
│   |   ├── Wheelcollider
│   |   ├── Suspension (Script)
│   |   ├── Trail Emitter (Script)
│   ├── Front Right Wheel
│   |   ├── Wheelcollider
│   |   ├── Suspension (Script)
│   |   ├── Trail Emitter (Script)
│   ├── Back Left Wheel
│   |   ├── Wheelcollider
│   |   ├── Suspension (Script)
│   |   ├── Trail Emitter (Script)
│   ├── Back Right Wheel
│   |   ├── Wheelcollider
│   |   ├── Suspension (Script)
│   |   ├── Trail Emitter (Script)
│   ├── CenterOfMass (Transform)
│   ├── Boost and smokes particles...

WheelVehicle script

This is the main script of the package controlling the behaviour of the cars, inputs and effects. The inspector is divided in the next 5 parts

Inputs

This is the list of inputs names used by the car. You can change them as you want and you can also use the same input for drift and boost to add some dramatic drifts to the cars. If you do not want the car to be controlled with Inputs just set IsPlayer to false. You can then use the variables Speed, Brake, Jump, Boost and Drift from scripts to to control the cars. This is usefull if you're makin an IA or controlling the cars in other ways. For exemple this was used with a hinge joint to manualy steer a vehicle in VR.

Finaly an AnimationCurve name Turn Input Curve is used to have a non linear steering. The value used in the prefabs is a good exemple giving more precision to the player

Wheels

You have two list of wheels: the drive wheels and the turn wheels. 4 wheel steering isn't supported in the current WheelVehicle script as they all steer in the same direction but it can be added if needed, just let me know.

Behaviour

Motor Torque: Animation curve representing the motor torque in Newton depending on the speed of the car. Having a negative torque after the top speed prevents going faster in some conditions
Diff Gearing: The differential gearing applyed between the motor and the wheels.
Brake Force: The power of your brakes, mostly determinesif we can lock the wheels.
Steer Angle: Maximum angle of the turn wheels
Steer Speed: Reaction speed to the inputs, basicaly gow low for old cars and high for cars with power steering
Jump Vel: How high do you want to jump?
Drift Intensity
Center Of Mass: I'd recommand using a center of mass a bit lower than the middle of the wheels to stay upright but don't go under the ground.
Downforce: How much downforce the car generate when rolling, should be high for sports car
Handbreak: bool
Speed: read only indication of speed

Particles

List of gas particles, the emission rate is then indexed on the throttle value.

Boost

Bosst: current boost available
MaxBoost: Max value allowed for Boost
Boost Regen: per second
Boost force: the bost is a force applied to the body, you should adjust this depending on the mass of the vehicle.
Boost particles and sounds

Other Scripts

Engine sound manager

Goes next to the wheelvehicle and emits sound depending on the state of the vehicle. This is a very basic implementation and I would recommend looking at some FMod tutorials to make your own improved car engine sounds ;)

Suspension

This scripts goes next to WheelColliders and offers a way to keep the wheel model where the WheelColliders is on realtime depending on the terrain. You might need to adjust the local rotation offset to get the wheel's rotation right

Trail emmiter

This script emits trails when the wheels start sliding around and drifting. The generated mesh as it's defaults and will be updated in the future

Camera Follow

Basic script used to have a camera following the cars in the demo scene, feel free to reuse it.

Ghost

A Ghost script and Ghost recorder are provided to save your cars time and movement. Basicaly use the GhostRecorder to record and put a Ghost script on the ghost you want to replay. Exemple will come but don't hesitate to ask me if you have any questions about this.

Extended version

The extented version adds some prefabs to show a bit more of what you can do with ACP. The most interesting exemples are the drift car, the motorbike and the tank.

Exemple

You can find a project I made using this asset and all the features one my GitHub under the name Autober. If you just want to test it you can find a compiled version of autober on itch.io